Multi-Point Bacterial Abatement System is intended to be a component of the International Space Station's Water Recovery System. M-BAS implementation would result in the reduction of precipitate currently impacting ISS water recovery. Equipped with M-BAS, the WRS could recover more water – contributing to more sustainable ISS operation.
According to a January 2006, SAE Technical Paper “Status of the Regenerative ECLSS Water Recovery and Oxygen Generation Systems” and the follow up in May 2012, “Status of the Regenerative ECLS Water Recovery System” (2), urine pretreatment chemical sulfuric acid combined with calcium lost from astronaut’s bodies through micro-g induced hypercalciuria. The resulting compound precipitates as calcium sulfate solids. Therefore there is a correlation between the amount of bacterial pretreatment chemical and the amount of solids forming later on inside the water recovery system. If it is asked of the Urine Processor Assembly to extract larger percentages of water from incoming urine, there is increasing risk these solids will precipitate in a component of the UPA called the Distillation Unit and cause it to fail. Thus recovery above 70% cannot be achieved sustainably.
To increase the performance of preexisting hardware is to significantly reduce the amount of solids in the feed before it reaches the DU. Reducing the amount of pretreatment chemical will reduce the amount of precipitate. But reducing pretreatment chemical would be detriment to the mechanical and sensor components of the water recovery system as uncontrolled bacterial populations lead to bio fouling.
UV water treatment is criticized for its lack of point source application like that of chemical treatment. However a multipoint UV treatment solution would control bacterial growth throughout a system by drawing feed from multiple points. Worldwide UV water treatment is increasing in popularity because it is effective and economical. UV avoids the use of chemicals, is compact and powerful enough for individual homes or an entire city like New York.
1) M-BAS interfaces seamlessly with pre-existing ISS hardware.
2) Prior to each UV treatment cycle solids are dropped out of suspension in a turbidity reduction/flocking unit.
3) The feed passes to UV unit where it receives bacterial control treatment in the form of UV light.
4) Isolated feeds are cycled back into respective pathways.
5) UV treatment is encapsulated into one contained unit.
6) M-BAS allows preexisting hardware to perform at a higher rate of water recovery, affording an increase in the number of crew members performing operations and reducing the need for costly water resupply from Earth.
7) M-BAS is capable of maintaining ISS Urine Processor Assembly bacterial levels with substantially less pretreatment chemical.
8) M-BAS operation aboard the ISS is both an economical and sustainable improvement over current operation by increasing water recovery by at least 15% to a total of 85% with a crew of 6 astronauts and a processing demand of 1.6 liters a day.
9) Each M-BAS service and maintenance procedure can be performed by one person in less than 30 minutes.